Cathodic protection system



Jan 6, 1970 E. D. LOYD CATHODIC PROTECTION SYSTEM Filed May 11, 1967 INVENTOR.

E.D. LOYD ATTORNEY United States Patent O 3,488,275 CATHODIC PROTECTION SYSTEM E. D. Loyd, Broken Arrow, Okla., assignor to Kaier Aluminum & Chemical Corporation, Oakland, Calif., a corporation of Delaware Filed May 11, 1967, Ser. No. 637,681 Int. Cl. C23f 13/00 US. Cl. 204-197 8 Claims ABSTRACT OF THE DISCLOSURE A cathodic protection system wherein a galvanically active metal anode is positioned in a water permeable fabric container and a stripable water-resistant or waterimpervious cover is adhesively bonded to and envelopes the water permeable fabric container so as to protect the anode from moisture until ready for use and act as a Shipping baler to protect the fabric container from physical damage in shipping.

BACKGROUND OF THE INVENTION This invention relates to cathodic protection systems and particularly to the protection of underground corrodible metal structures such as pipe lines, steel structures and the like and to protection systems utilizing them.

Undeground structures such as pipe lines, oil well tubing, steel structures and the like, have been afforded cathodic protection by employing galvanic systems including burying anodes of a metal electronegative to the structure, ordinarily, magnesium, aluminum or zinc or alloys thereof, in the vicinity of such structures and electrically connecting them thereto. The structure is thus rendered cathodic to its soil environment by means of the flow of current from the anode to the structure, and accordingly, corrosion due to electrolysis is greatly minimized. Normally, the sacrificial anodes are placed in a fabric bag together with a suitable backfill composition and the top of the bag is secured. The backfill is designed particularly to control the chemical nature of the anode environment and thereby maintain perfect contact of the anode with the earth. Backfill compositions are Well known in the art, usually mixtures of clays, such as gypsum, bentonite, and calcium or sodium sulfates. This fabric bag is then placed in a water impermeable or water resistant bag of paper or plastic film for shipment.

SUMMARY OF THE INVENTION It is an advantage of the instant invention that it provides one complete cathodic protection system doing away with these separate packaging operations. It is an advantage of the instant invention that it provides a cathodic protection system protected from the adverse influences of moisure until ready for use but yet is easily placed in service. It is a further advantage of the instant invention that it provides a cathodic protection system such that current distribution and anode consumption can be effectively controlled to meet any given need. It is a further advantage of the instant invention that it provides a shipping container or baler for physical protection during handling and shipping.

According to the instant invention, the cathodic protection system comprises a galvanically active metal anode encased in a water permeable fabric container. A stripable water-resistant cover is adhesively bonded to and envelopes the water permeable fabric container so as to protect the anode from moisture until ready for use and protects it from damage in shipment. Desirably, the adhesive bonding material on the cover preferentially adheres to the cover rather than the fabric whereby the adhesive does not adversely effect the water permeable quality of the fabric container when the cover is removed therefrom. The paper cover may also be only discontinuously bonded to the fabric container. This enhances its stripability from the fabric container i.e. its ability to be stripped from the fabric container. The cover may also be crinkled so as to be stretchable with the fabric container and also to provide a grip for stripping the cover from the fabric container. If desired the cover can be substantially water impermeable rather than just water resistant. This will provide greater protection for the anode. The cover can be of any suitable material e.g. paper or perhaps one of the many well known plastic films. The cathodic protection system normally will include a granular anode backfill composition filling the space between the anode and the fabric container. If desired, a tear-tab may be provided on the cover so as to facilitate stripping the cover from the fabric container. It is also within the scope of the instant invention to so bond the cover to the fabric container that only portions of the cover are stripable from the container. This will leave behind portions of the cover adhering to the fabric container which can be used to control the current distribution and anode consumption.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is an elevation view, partly in section of one embodiment of the instant invention.

FIGURE 2 is an elevation view of another embodiment of the instant invention.

FIGURE 3 is a top sectional plan view taken along line 3-3 of FIGURE 2.

FIGURE 4 is an elevation view of another embodiment of the instant invention.

FIGURE 5 is an elevation view of yet another embodiment of the instant invention.

DETAILED DESCRIPTION With reference now to the drawings wherein the same reference numerals have been applied to corresponding parts, it will be seen that the anode comprises a cylindrical element 10 of aluminum, magnesium, zinc, or their alloys or other suitable metal within which there is secured a connector 12 which may be for example a straight rod or a coil as shown in the figures. The upper end of connector 12 projects from the anode cylinder 10, which for this purpose may be formed with a depression or recess 14 and insulated cable 16 is attached to the connector in a manner to produce electrical continuity with the other end of cable 16 being used for attachment to the structure to be protected. Recess 14 is thereafter filled with insulating substance 18 for example bitumen. The anode is encased in a water permeable fabric container 20. Normally, the space between the anode cylinder 10 and the fabric container 20 is filled with a suitable granular anode backfill composition 22. A stripable waterresistant cover 24 is adhesively bonded to and envelopes the water permeable fabric container 20 so as to protect the anode from moisture until ready for use. The waterresistant cover 24 is constructed of paper or other material heavy enough to act also as a shipping baler to protect the fabric during handling and shipping.

The adhesive bonding cover 24 to fabric container 20 may be any suitable adhesive. Common sizing works quite well. The term sizing refers to any of various glutinous materials (as preparations of glue, flour, varnish or resin) used for filling the pores or surfaces (as of paper, textiles, leather, or plaster) or in book bindings for applying color or leaf to book edges or covers. Within this large class of well-known materials it is very easy to select material suitable for the instant purpose. Pressure sensitive adhesives are also very satisfactory. The

adhesive bonding material desirably adheres to the cover 24 rather than to the fabric container 20 so that the adhesive does not adversely effect the water permeable quality of fabric container 20 when the cover 24 is removed therefrom.

The cover 24-fabric container 20 assembly may be prepared in many ways. The assembly may be provided as a roll in the form of a tube closed along one side as by stitching 26. The desired length may be severed from the roll of material and one end closed as by stitching 28 so as to form the bottom of the container. If desired, as shown in FIGURES 4 and 5, the bottom corners of the assembly can be folded over and hemmed dog-cared as at 20. This construction strengthens the corners and bottom of the cathodic protection system somewhat.

The adhesive, instead of uniformly but weakly bonding the cover 24 to the fabric container 20 may be discontinuously distributed so that the cover 24 is bonded to the fabric container 20 at separated points. This enhances the stripability of the cover 24 from the fabric container 20.

If desired, as shown in FIGURES 1, 4, and the cover 24 may be crinkled as at 32. The crinkling 32 provides a grip which makes it easier to strip the cover 24 from the fabric container 20. In addition, the crinkling 32 makes the cover 24 stretchable with the fabric container 20, thus enhancing the durability of the system. The crinkling 32 may be horizontal as shown, or vertical, or random as desired. As shown in FIGURE 2, the cover 24 may be of smooth paper or plastic film if desired.

The optimum procedure is to make cover 24 of substantially water impermeable material. This porvides optimum protection for the entirt system until the cover 24 is removed and the anode is placed in service. However, since human beings are fallible, it is likely that some people [might install the system and place it in service with the paper cover 24 intact. To allow for this human error it is desirable that the cover 24 be made of water resistant rather than substantially water impermeable material. Then, if someone should make a mistake and install the system with the cover 24 intact, permeable but resistant cover 24 will only retard the function of the anode for the short period until it is finally permeated with water and normal current flow is obtained.

As shown in FIGURE 2, a tear tab 34 may be provided in the cover 24 to facilitate stripping the cover 24 from the fabric container 20. As shown in the figures, the entire system may be secured at the top by a tie 36.

As shown in FIGURE 5, adhesives of varying strength can be used in such a way that only portions of the cover 24 are stripable from the fabric container 20. This provides a system wherein part-s of the water permeable fabric container are blocked off by the water resistant or substantially water impermeable cover. As is well known in the art, the current distribution to the cathode from the system can be controlled in this way and the rate of anode consumption .can also be selectively controlled.

While there have been shown and described hereinabove possible embodiments of this invention, it is to be understood that the invention is not limited thereto and that various changes, alterations, and modifications can be made thereto without departing from the spirit and scope thereof as defined in the appended claims wherein what is claimed is:

1. A cathodic protection system comprising:

(a) a galvanically active metal anode;

(b) a water permeable fabric container encasing the anode;

(c) a stripable cover adhesively bonded to and enveloping the water permeable fabric container, said cover being sutficiently water impermeable so as to protect the anode from moisture until read for use.

2. The cathodic protection system of claim 1 wherein the adhesive bonding the cover to the fabric container preferentially adheres to the cover rather than the fabric whereby the adhesive does not adversely effect the water permeable quality of the fabric container when the cover is removed therefrom.

3. The cathodic protection system of claim 1 wherein the cover is discontinuously bonded to the fabric container whereby its stripability from the fabric container is enhanced.

4. The cathodic protection system of claim 1 wherein the cover is crinkled so as to be stretchable with the fabric container and so as to provide a grip for stripping the cover from the fabric container.

5. The cathodic protection system of claim 1 wherein there is a space between the anode and the fabric container and a granular anode backfill composition fills the space between the anode and the container.

6. The cathodic protection system of claim 1 wherein a tear tab is provided on the cover so as to facilitate stripping the cover from the fabric container.

7. The cathodic protection system of claim 1 wherein only portions of the cover are stripable so as to control current distribution and anode consumption.

8. The cathodic protection system of claim 1 wherein the cover is of paper.

References Cited UNITED STATES PATENTS 2,111,025 3/ 1938 Galler.

2,127,012 8/1938 Spangler et a1. -1 2,525,665 10/1950 Glesner et al. 204-197 2,722,311 11/ 1955 Morrison 229-31 2,976,226 3/1961 Risberg 204-196 3,012,958 12/1961 Vixler 204-19 7 3,260,661 7/1966 Kemp et al 204-197 T. TUNG, Primary Examiner US. Cl. X.R. 

